More tests for pattern using

[agocke]

Follow up to #27729

Jared suggested a variety of useful tests that weren't included in the original PR. They are:

• Tests to ensure we bind correctly when presented with the pattern + an interface implementation
• Tests where the receiver is a generic parameter constrained
  • To an interface that implements an interface that meets the disposable pattern but is not IDisposable
  • To an interface that implements an interface that meets the disposable pattern and implements IDisposable
  • To an interface that does not meet the disposable pattern directly but indirectly through an extension method.
  • The first two items above but additionally with the struct constraint and IL verification that we call Dispose in a non-boxing fashion.

We should follow up with these before merging the final feature branch.

[chsienki]

These are no longer relevant; the only time we allow pattern based disposal is for ref structs, which can't implement interfaces.